Good post, ive had the same issues and found that only 2 things ever fix it (for me) - Changing Memory usage on advanced options (Default to high or vice versa) - Changing your resolution. No other fix has worked but these 2 combined has not yet failed to sort it out and dont involve having to leave or quit the game. Also, i second the "not on XP" thing my mate runs XP and hasnt ever had this issue